Pumping system



March 28, 1933. H. E. .LA BOUR 1,902,961'

PUMPING SYSTEM Filed July 14, 195o l2 Sheets-sheet 1 FROM EEN/,12N L//VE --F/ /M 22' 52 ,2/ --4 f T/ Patented Mar. 28, 1933 UNITED STATES HARRY E. LA Bonn, or ELKHART, INDIANA PUMPING SYSTEM Y Appiication inea .Tiny 14,

The present invention relatesgenerally to pumping systems, and more particularlyto pumping systems capable of handling a mixl ture of liquid and gas. vSpecifically,` the present invention contemplates the provision of an improved pumping mechanism for maintaining a vacuum "upon the radiators of a steam heating system and for returning the water to the boiler.

As is well known to those skilled in the art, steam heating systems are now comlmonly in use employing steam at a relatively low boiler pressure and employing a vacuum circulating pump for maintaining la circulation to the radiators and for withdrawing the condensate and waste steam, if any, together withany Aair Vwhich may leak into the system. In suchinstallations it is desirable to return the condensate to the boiler, butitis undesirable to direct any of the air into the boiler. It is therefore essential to separate out the air, condense the steam which isV not already condensed and return the total condensate to the boiler.

In my previous patent, No. 1,674,115, 'issued June 19, 1928, I disclosed an improved steam heating system including a novel pumping apparatus for maintaining a vacuum upon the return line, separating out the air, condensing the steam and returning the condensate to the boiler. The system there disclosed employed a relatively small high speed centrifugal pump capable of pumping gas, vapor, or liquid, or a mixture of them, and produced a positive suction when pumping any of said fluids.v One object of the present invention is to provide an improved construction of that type and one which is simpleA and inexpensive yet exceedingly effective in operation. Y`

@ther objects and advantages of my invention will be apparent to those skilled in the art after a considerationv of the followinggdetailed description ofthe same,rtalen in ,conjunction with the accompanying drawings,

in which:

Figurefl isla diagrammatic view illustrating one embodiment of my invention; and

Figure 2 is a diagrammatic view illustrating another embodiment of my invention.

1980. SerialV No'. 467,830.

erence numeral 1 indicates in its entirety a centrifugal pump having an intake 2 and an j outlet 8. Preferably, the pump 1 is of the type shown in my prior Patent No.'1,578,236, f

issued March 28, 1926, but this is not entirely necessary in the pumping system of the present invention. Any self priming pump or any pump which will handle some air will be satisfactory and, `as a matter of fact, my improved system can be made to operate with a pump which will not handle air, although pumps of the first type are preferable. i

The outlet or return line from the radiators is indicated by the reference numeral 5, and this actually forms theinlet side of the pumping system as a whole. Check valves 6 provide a one-way flow from the line 5 Vthrough the intake branches 7 of the pumping system. A pair of chambers or containers 9 are. shown as connected at their upper ends to the intake conduits 7, as by means of short sections 10. The sections 10 are so connected that they are also in communication with the outlet conduits 12 of the pumping system, these outlet conduits being connected to the boiler by means of a discharge line 13. Y f As illustrated in the drawings, these conduits 7 and 12 are shown as connectedV toa radiator return 5 and a single boiler line 13, respectively, but it is obvious that the conduits 7 and 12 may have separateleads .connected thereto if found desirable or necessary. i v

The containers 9 are each provided with a valve 15 having a ball 16 at the upper end and a float 17 at the lower end, the ball 16 and float 17 being connected to one another by means of a stem-18. The ball 16 is provided with a closure 2O adapted to be received by a correspondingly formed apertured seat 21 provided at the upper part of each of these containers or chambers 9. .The particular function of this valve, as Vwill be better understood later, is to allow theescape of gas from the container or chamber 9 but to pre- Referring now to the drawings, the refvent the escape of liquid therefrom, this bev l ing accomplished by virtue of the buoyancy of the iioat 17 which, rising with the level of the liquid in the chamber 9, serves to close the opening at the top of said chamber.

The lower part of each of the containers orrchambers 9 is adaptedto be placed in communication with the intake and the outlet of the pump 1 alternately by a system of conduits and interlocked valves which will now be described. VLeading from the bottom of` .the yvalve 26 is connected with .the intake 2 of the pump by means of a branch 30.

The valves 2.2 and 26 are connected together by means indicated diagrammatically by the reference numeral 32. It is desirable that these valves operate simultaneously, and in order tosecure this result each valve may be provided with a pulley or sprocket wheel over which is trained a chain or belt. My invention also contemplates mounting these valves 22 and 26 on the same shaft and, actually, this construction is the preferable form. As above stated, the valves 22 and 26 are of the two-way type, sometimes known as the two port type, and these valves areshiftable from one position to another so that iiow from branches 29 and 30 can be directed, respectively, to branches 21 and 24 in either one direction or the other. y

The operation of the 'structure so far described is as follows. As illustrated in Fig ure 1, it being assumed that the pump 1 is in operation, liquid is withdrawn from the "right hand chambers 9 through the branch 20 atV the branch 30 and passing through the pump 1 is then directed upwardly through branch 29 past the valve 22 which directsvthe liquid to the left, as viewed in Figure 1, to

the branch 21 and into the left hand chamber 9'. f Since the buoyancy of the float 17 serves to hold the valve 20 21 closed, the liquid is forced to pass out of a chamber 9 through `the section 10 and past the check valve 11 which permits only outward flow into the outlet conduit 12 and the boiler line 13, from which the liquid is ypassed back into the boiler. y' y When the valves 22 and 26 are shiftedto their other position, and this is the position illustrated 'in Figure 2, the operation of the pump 1 withdraws liquid from the left hand chamber 9` down through the conduit 20, through the Vbranch 24, past the valve 2'6, into the conduit 30 and into the intake side 2 of j the pump 1. In the meantime the liquid discharged'through the outlet 3 of the pump 1 passes through the conduit 29, past the valve 22, to the right inthe branch 21 and upwardly through the conduit 20 and into the chamber 9 on the right hand side, as viewed in Figure 2.

Digres'sing for the moment, I shall now describe the control means for automatically shifting the interlocked valves 22 and 26.

Turning to Figure 1 it will be observed that a pipe 35 opens into communication with theY conduit 29 near the discharge side 3 of the pump 1. The outer end of the pipe 35 is 'i connected to a diaphragm chamber 36 containing a diaphragm 37, the latter being Hexible yet substantially liquid and gas tight. The pipe 35 leads into the lower part of the diaphragm chamber 36 and below the diaphragm V37 therein, while the upper part of the diaphragm chamber 36 is provided with a port 39 through which rises a stem 40 connected at its lower end to the diaphragm 37. A spring 42 is connected at one end'tofthe stem 40 to urge the same downwardly, the spring 42 being tensioned between the stem 40 and an abutment 44 fiXedly mounted upon any stationary part, such as a casing 45 enclosing the valve shifting mechanism proper.

Mounted in the casing 45 is a ratchet wheel 47 provided with a plurality of ratchet teeth 48 which are adapted to be consecutively engaged by a latch or pawl 49 pivoted to the stem 40 near the upper end thereof. The ratchet wheel 47 may have an outer periphery in the form of a pulley over which is trained a belt 51 having a connection with the interlocked valves 22 and 26 in any manner desired.

It is to be understood, however, that the motion transmitting mechanism operatively extending between the stem 40 and the Valves 22 and 26 may take any form desired and that thel particular structurejust described is only one conventional way of securing the result of controlling the valves 22 and 26. Obviously other means may be provided for the same purpose, for instance, the shaft upon which the valves 22 and 26 are fiXedly secured may be extended and directly connected to some form of ratchet mechanism, such as that indicated by the reference numerals 47 and 48. It is desirable that in practice the valves be shifted with a snap action and for that purpose a spring, spring cage, catch and trip of the type shown in Pfau Patent No. 1,090,873 or Perry Patent No. 933,200 may advantageouslyk be employed. Also, as illustrated in those patents, the rotary valve or valvesy may be replaced by a plurality of poppet valves.

Furthermore, while I have shown the pipe l35 opening into the outlet pipe 29, it is con- Vthe reversing motor and to a separate field reversing motor 67 and leads 68V connected with a power line. As clearly shown in Figure 2, the float 60 in the left hand chamber 9 is provided with a similar system of contacts 62 which, like the contacts 62 of the right 'hand chamber 9, are adapted to close an electric circuit through conductors including fixed contacts 64. The conductors 66 for the` left hand chamber 9 lead to the armature of of the same,as indicated in Figure 2. As is well understood in the art, the motor 67 may be driven in one direction or the other, depending upon which one of the fields is acti- `vated byy directing aV flow of current theredirection of drive, the motor may drive in thesame direction in successive steps.

As stated above in connection with the embodiment illustra-ed in Figure A1, any suitable means may .be employed to transmit motion between the reversing motor 67 and the interlocked valves 22 and 26, and it is to be understood that while I have shown one conventional structure for shifting the valves 22, 26 any,7 equivalent structure falls within the scope of my invention.

The operation of my complete pumping system is as follows. When the valves are in the position illustrated in Figure 1 the operation of the pump 1 draws condensate from the radiators through the return outlet 5 into the right hand conduit 7 forming the intake of my improved pumping system. The suction applied is effective to lift the check valve 6 allowing the condensate, together with any air drawn into the heatingsystem, to flow through the short section 10 and into the right hand chamber 9. The suction createdby the pump withdraws liquid from the right hand chamber 9, which liquid actually acts as a liquid piston in the container 9. The air and liquid condensate separate in the chamber 9, the chamber 9 thus acting as a trap to retain the air and' other gases in the top of the chamber while the separated liquid fallsl to the bottom of the chamber and is withdrawn therefrom by the action of the centrifugal pump 1. In normal operation, however, the amount of liquid drawn into the pumping system is not suflicient to supply the demand of the pump 1. This occasions a fall of the liquid level in that chamber. and,

as is well understood in thev art, as soonas air passes over from the chamber 9 into the conduits20 and 30 and from thence into the pump'l the discharge pressure thereof immediately falls. pressure on the lower side of` the diaphragm 37 previously maintained by" virtue of the discharge pressure of the pump is suddenly released and the ,springV 42 immediately moves the stem 40-downwardly.` The downturn, drives the valves shifting means 32 to swing the valves 22, 26 to their opposite position, this position being the same as that shown in Figure 2. By virtue of the sudden releaseof the discharge pressure due to the introduction of gasin the intake, the shifting ofl the valves 22, 26 is, as a practical proposition, substantially instantaneous. As soon as the valves 22 and 26 are shifted from the position shown inFigure 1 to a position corresponding to that shown inFigure 2 the intake 2 vof the pumpv 1 isconnected through the conduit 30, the left hand branch24, and

Athe conduit 2O to the left hand chamber 9 which, as shown,is filled with liquid. As soon as the suction of the pump is exerted upon the lefthand chamber 9 the check valve 11 closes.l This prevents 'any back flow `of liquid from the boiler line 13. `The continued suction of the pump 1 withdraws liquid froml the chamber 9, and since Ino more liquidcan enter-'from'the boiler line 13 suction l1s created withinthe left'hand intake'conduit-T,

hand chamber 9 and the-right hand conduit 7, suction is now applied to the same return line 5 throughthe left hand Container 9 and the left hand conduit 7 As the level of liquid in the container 9 continues. to fall the valve 15 is allowed to fall, but air is prevented from enteringthe lcontainer 9 by virtue of the gas tight seat eifected'between the wall 16 `and the valve seat 19. In the meantime:

thev pump 1 has been discharging liquid out the outlet 3 into the conduit 29 and passing the same to the right to thelbra'nch 21 and back into the right hand chamber 9. The

level of liquid in this chamber therefore rises"- As soon as this occurs the 'f Vhere Vbeforesuction wasl applied to toY and,'acting asa liquid piston, first drives the air and gas therein out through the port 21 and lifts the ball` 16 from its seat 19. As the Vboiler pressure inthe boiler line 13.

When the level of liquid in the right hand container 9 approaches the top thereof, substantially all the excessair and gas has been expelled, and as the float 17 rises the port 21 is closed, so that liquid can not escape to the atmosphere but is forced to pass through the short section 10 and, the right hand valve ,6

being already closed, is directed through the right hand check valve 11 and up the outlet conduit 12 into the boiler line 13. The other check valve 11 effectively resists any tendency for the liquid to pass downv the left hand conduit 12 and into the left hand chamber 9, thus assuring that the liquid will be directed to the boiler.

It is thus obvious that the falling liquid level in the left hand chamber 9 will act as a liquid piston drawing in condensate and air from the radiator return line while the rising liquid level in the right hand chamber 9 acts as a liquid piston to, first, expel excess air and gases from the chamber and, second, to direct a quantity of liquid to the boiler line 13. "When the liquid level in the left hand chamber 9 falls to such an extent that air is drawn into the intake 2 of the pump the pressure on the outlet side thereof immediately falls, which reduction instantaneously allows the spring 42 to force the stem downwardly, thereby shifting the interlocked valves to the opposite position.

In efect, therefore, I pro-vide a pumping system employing a pair of liquid pistons which are alternately raised and lowered by an actuating mechanism vincluding a pump. An important feature of the present invention is that the liquid drawn in by the operation of the pumping device is added to the residual liquid in the chambers and that the pump operates to force the liquid in one direction until the supply thereof from the other direction is substantially depleted. Thus while the pumping system itself opcrates with a predetermined quantity of liquid, the amount of liquid added thereto by the intakesystem from the return lines will cause an equal amount of liquid on the other side of the system to be forced back into the boiler. In addition, on the upstrolre of the liquid system excess gases and uncondensed vapors are removed from the chambers containing the liquid pistons. so that there is no likelihood of forcing anything but liquid into the boiler. Y

This is an important feature of the present invention. The structure' provided thus acts not only as an efficient pumping system but'y alsoas a means for separating a gas and a liquid when they are received as a mixture. With this in mind it will be observed that the present invention may be employed in instal lations entirely different from steam heating systems. For example, the present disclosed apparatus can be employed where the principal function thereof is to separateY a gas from a liquid. For example, where the pres-V ent system has been described as connected to a steam boiler on the discharge side of the sys tem and to the radiator return line on the intake side of the system, it is possibleto connect the intake sideof the system directly to the discharge side interposing forthat purpose, a simple container whichA would supply only a suliicient head to be adequate to cause the rising liquid piston to force the Vexcess gas out the valve 15 rather than through one of the check valves 11 and into the container,

In this way the present` apparatus would function efliciently as a gas and liquid separator. Furthermore, if the gases to be-expelled contain valuable substances it would be a simple matter: to connect leads to thements 37 or under the control of the iioat controlled switches (S1- 611, as is-well understood in the'art. Furthermore, such a system can be made to be responsive, primarily, to

either a fall of pressure on the discharge side Y of the pump or to a predetermined lowlevel Y of liquid in the chambers 9. It shouldbe here pointed out, however, that whether the valve shifting mechanism is made responsive, initially, to a fall of pressure or fall of liquid level in the chambers 9, either of such valve operating mechanismis actually responsive to an excess of gas compared to the liquid in the chamber. This will be understood by comparing Figures 1 and 2. `In Figure 1, when the level ineither chamber 9 falls sufficiently to allow air to be drawn into the pump, the valve shifting mechanism operates to reverse the iiow and draw the liquid out of the filled chamber and direct it into the emptying chamber; and in Figure 2, when the level falls sufliciently to cause the oat` arm 61 to complete the electric circuit, the valves are shifted to reverse the flow in the manner and which are shown in the drawings, theV actual reversing of the valves is in practice made practically instantaneous. It has been'` pointed out above that as soon as any air or gas obtains access to the pump l the discharge Y pressure immediately falls; hence the valves 22 and 26 are immediately shifted. In the modification illustrated in Figure 2, as soon as the level in either chamber reaches a predetermined minimum, the circuit is closed and the valves are immediately shifted. It is tobe understood, moreover, that any other form of snap action may be substituted such as, for example, a spring placed under tension and released after a given stress or position has been reached, as is common in the art. i

It is also to be understood that, insteadV of separate branches 21 and .24,- these branches might take the form of conduits cast or other-` wise formed in a single manifold, in which case the valves 22 and 26 would preferably be formed as a structural whole.

VThere is contained in this system a peculiarly neat concept of means and mode of pumping a mixture of gas and liquid in that the liquid can mingle with and become a part of the displacing medium. At each stroke the excess of liquid is removed and just the right amount of displacing medium retained, but the system is operative whether the two chambers are alike or not.

In the form shown in Figure 1 the pump l may actually exert' a suction, as it is a self priming pump, but the system doesvnot re-V quire a self priming pump, a straight'centrifugal pump developing sufficient pressure to discharge the liquid into the boiler being sufficient. Y

Also, instead of making the system double acting, it may be made single acting. For

example, in Figure 2, if the right hand tank is made large enough to serve as a reservoir between discharge strokes it may serve merely as a liquid receiving tank. i

The chambers 9 are the actual pumping chambers and it is in them that the suction is produced which causes the inflow of gas and liquid. The gas and liquid then separate and are stratified by gravity, the liquid being added to the liquid piston which then is raised to expel the gas and linally to expel a part of the liquid in excess of that required to fllthe chambers. I believe that this mode of operationis broadly new. f

The motor of the pump lrmay be under the control of a vacuum gauge or suction re` sponsive elementso-that where a predetermined vacuum has been attained the pump l may be stopped.-A This might cause shift-- Ving ofthe valves 22, 26 but the system may be started into operation in any position without difiiculty by merely starting the-- pump 1- WhilelI have described in connection with the accompanying drawings the preferred embodiments of my invention, it is to be un-V derstood that my invention is not to be limited to the structure shown or described, but that, in fact, widely different means may be employed in the practice of the broader aspects of my invention.

What I claim, therefore, and desire to se` cure by Letters Patent is:

l. The method of pumping.` a lmixture of gas and liquid which comprises trappingy said mixture in two separate bodies to separate the gas and liquid in each, pumping out the liquid from one body until gaspasses over, pumping liquid from the second body and directing thev same into said irst body whereby to drive off the gas, y pumping until gas passes over from the second body, reversing the pumping operation to again pump liquid from the firstbody into the second to drive off the gas therein, and continuing said pumping operation until gas passes over from the first body.

traps therein, the method of operation which comprises alternately. drawing a mixture of continuingfsaid V rectingl the trapped gas toa point of discharge at each alternation by pumping liquid into the trap containing the gas from the other trap and from the inlet line'and continuing the flow until substantial failure of the pump due to excess gas', and then reversing the pumping operation. v

3. A system for pumping a mixture of gas and liquid', comprising, in combination, a centrifugal pump, apair of chambers, an intake conduit system, an outlet conduit system,`

valved connections connecting said chambers to said systems and said pump and including a pair of interlocked valvesoperable to con.-

nect the inlet side of the pump to said intake conduit through either chamber and tocon-` neet the discharge .side of the pump to the outlet conduit system through .the other of said chambers, yand means including relief valves for the chambers and responsive .to the discharge head of said pumpk forshifting said interlocked valves to reverse the connections between the chambers and said pump Y 100. 2. In a pumping system having aninlet Y line and an outlet line and a pair of valved `ber is'connected to the discharge side ofthe pump when said valves are shifted.

and conduit systems whereby gas trapped in the chamber initially forming a continuation of the intake conduit is expelled as said-cham- 4. In a system of the class described the combination of a pair of liquid containers, a pump, connections from the containers to a discharge linev and to an intake line, valve means controlling said connections, and pressure responsive means connected to said pump and operative to control said valves to alternately withdraw liquid from one of said containers and direct it to the other.

5. In a system of the class described the combination with an intake line and a discharge line, of a pump, a pair of containers, each having valve means operative to allow the egress of gas and to prevent the egress of liquid, 'reversible connections between the inlet and outlet of said pump to said containers, whereby each of said containers .are

. adapted to form a continuationof said 'intake or discharge line alternately, connections from each of said containers to the intake line and to the discharge line, and means responsive to dischargepressure of the pump for controlling saidconnections. l s

6. In a pumping system of the class described the combination with an intake line and a suction line ofa pair of containers connected in and forming a part of said lines, a liquid tight gas outlet valve near the top of each container, a pump, connections be-` tween said containers and the pump and linesv whereby aV mixture of gas and liquid may be `and liquid discharged through the other, and electrically operatedmeans' responsive when drawn in through either of said containers gasreaches a certain point in the suction line through which the mixture is being admit- Vted for reversing said connections, thereby Y Pump directingliquid into the last'mentioned coni tainer and expelling the gas therein through the valve associated with that container.

V7.l In a system for pumping a'miXture of gas and liquid, means forming a pair of liquid pistons,

an inlet line and an outlet line, valved connections operatively connecting the pistons to said lines, and means'responsive lto the discharge head of said pump for controlling saidV valved con- A .'nections.

8. A `system for pumping a mixturev of liquid and gas comprising, in combination, a intake and delivery lines connected therewith, a pluralityvof valved containers each Yadapted to be connected to said lines, shiftable valve means alternately connecting the containers with the pump, loaded means Y biased to shiftl said valve means, and means controlled by the discharge head of said pump andV adapted'to prevent movement of said loaded means to shift the valve means as a pump for alternately raising and lowering said pistons,

long'y as liquid is discharged fromy said pum-p".- A

9. In a system for pumping a'mixture of liquid and gas comprising, in'combination, apump, intake and delivery lines connected therewith, a plurality of valved containers each adapted to be connected to said lines, shiftable valve means alternately connecting the `containers with the pump, a,V movable member the movements of which are adapted to shift said valves, and pressure responsive means connected to the discharge side of said pump for controlling saidymovable memberf 10. A system for vpumping a `miXturerofV liquid and gas comprising,.in combination, a pump, intake and delivery lines connected therewith, shiftable valve means alternately connecting the containers with the pump, and means adapted lto shift said valvev means when there is an excess of gas in the system.`V

11. In a pumpingl system including a liquid pump, a plurality of sourcesfof liquid supply, and operable connections putting said pump into communication with either of said sources, the method of vcontrolling said connections inaccordance with the discharge head of the pump. l v

12. In a pumping system including Va liq-` uid pump including intake and discharge passages,/ a plurality of sources of liquid supply, and operable connections putting said pump into communication withv either of `said sources, the method of controlling said connections in accordance with the pres;y sure in one of said passages.V f'

13. In a pumping system including a liquid pump having intake and discharge passages, a plurality of liquid holding'containers, operative connections between each of said containers whereby. each of said con-` tainers may be placed in communication with said pump, and means responsive'to the pressure in one of said passages for controlling said operative connections.

14. In a pumping system, means a pair of liquid pistons, a self priming pump capable of handling gas and liquids and including intake and discharge passages, valved lconnections operative to place said passages in communicationV with said means, and pressurev responsive mechanism for controlling said valved connections, said mechanism' being responsive to ypressure in at least one'of said passages. Y f c t 15. A pumping system for pumpinga mix-- ture of gas and liquid comprising, in combination, a self priming pump, Yintake and delivery lines connected therewith, apluralforming iio chambers, valved connections between the pump and chambers, and means responsive to the complete exhaustion of liquid from one chamber by the pump for automatically shifting said connections. Y

V17. In a system embodying a mixture of gas and liquid, the method of pumping which comprises trapping the mixture and at least partially separating the gas and liquid into two bodies, pumping out the liquid until gas passes over, and then reversing the pumping operation and expelling the separated gas.

18. In a system embodying a self-priming pump capable of handling a mixture of gas and liquid and a conduit for confining the same, there being a container disposed in and forming a part of said conduit, the method of pumping which comprises trapping the mixture in said container and at least partially separating the gas and liquid into two bodies therein, pumping out liquid from the liquid body until gas passes over, and revers-V ing the pumping operation to expel the gas.

19. In a system embodying a self-priming pump capable of handling a mixture of gas and liquid and conduit means for conning the same, the method of pumping which comprises trapping the mixture and at least partially separating the gas and liquid into two separate bodies, pumping out the liquid from the liquid body until gas passes over, next reversing the pumping operation and expelling the separating gas until the liquid in the conduit means reaches a certain point, then again reversing the pumping operation.

20. In a pumping system of the class de` scribed the combination with an intake line and a suction line of a pair of containers connected to said lines, a liquid tight gas outlet near the top of each container, a self-priming pump, connections between said containers and the pump and lines whereby a mixture of gas and liquid may be drawn in through either of said containers and liquid discharged through the other, and means responsive to the ratio of gas to liquid in the container through which the mixture is being admitted for reversing said connections, thereby directing liquid into the last mentioned container and expelling the gas therefrom.

21. Means for pumping a mixture of gas and liquid comprising, in combination, inlet and outlet conduit means, a self-priming pump, a pair of chambers, means alternately placing each chamber between said pump and the inlet conduit means and between said pump and the outlet conduit means comprising shiftable connections, and hydraulic head responsive means for shifting said connections.

22. A system for pumping a mixture of liquid and gas comprising, in combination,

intake and delivery conduit means, a pair of containers each adapted to be alternately connected in said intake and delivery means, reversible connections to eect said alternate connections, a liquid pump disposed below said containers, and means responsive to the exhaustion of liquid from the containers for reversing said connections.

In witness whereof, I hereunto subscribe my name this 10th day of July, 1930. Y

. HARRY E. LA BOUR; 

